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Can lead-free and lead-included PCB's use single process cleaning techniques?
In a recent study, lead free and lead-containing assemblers were sanitized using the same cleaning agents paving the way for the potential of cross contamination. The concern here is that cross contamination could infect 'lead-free' assemblers that can only contain .1% lead weight based on legislation.
Based on exposure time and the temperature of the cleaning agent, lead from a lead-containing assembler can be passed to lead free assemblers if lead has been dissolved into the cleaning agent used. The deposit from the lead-free to lead-containing agent can be deposited as elemental lead or as ionic re-contamination from one machine to another.
In the test, random customer examples were provided to analyze the levels of lead. All examples were taken from customer using the same assemblers and products. The experiment showed that the amount of dissolved lead in the cleaning agent had no reliance with throughput. The maximum levels of lead were consistently lower that 10 mg/1.
Measurements were taken from a variety of spots of the test substrates including the top, central and bottom regions in order to achieve statistical congruency. The measurements of the lead-free boards showed values of 0 - .3 mg/cm2. The critical limit of .1% was therefore not met. The analysis of the lead-included assemblers demonstrated measurements as low as 3.0 and as high as 5.0 mg/cm2.
Following four cross-contamination experiments with identical test boards, X-ray collected data from all areas of the assemblers showed that lead was neither transferred via redo reaction or ionic contamination. For the record, additional rinsing steps failed to alter the outcomes to any extent.
This test examined 500 lead-included assemblers that were cleaned using similar processes. Following the cleanings, lead-free test boards were cleaned using the exact same 'used cleaning agent at a wide array of temperatures. The lead content transfer, if any, was then analyzed and illustrated no significant increase in lead amounts in the lead-free assemblers.
The results demonstrate that a relatively small amount of lead is dissolved into a cleaning agent illustrating the ability to clean lead-free and lead-included agents using a single process without risk. It should be mentioned that the results seen only apply to individuals using similar cleaning agents to the ones used in testing. In contrast, it should be noted that cleaning agents with increased alkaline pH-values demonstrate a tendency to dissolve increased amounts of lead therefore increasing the risk of cross-contamination.
Results showed mixed cleaning process provide satisfactory results that meet current legislative requirements.
Test Provided by ZESTRON Europe, Ingolstadt, Germany
Click here for more news and industry related information resources.
Based on exposure time and the temperature of the cleaning agent, lead from a lead-containing assembler can be passed to lead free assemblers if lead has been dissolved into the cleaning agent used. The deposit from the lead-free to lead-containing agent can be deposited as elemental lead or as ionic re-contamination from one machine to another.
In the test, random customer examples were provided to analyze the levels of lead. All examples were taken from customer using the same assemblers and products. The experiment showed that the amount of dissolved lead in the cleaning agent had no reliance with throughput. The maximum levels of lead were consistently lower that 10 mg/1.
Measurements were taken from a variety of spots of the test substrates including the top, central and bottom regions in order to achieve statistical congruency. The measurements of the lead-free boards showed values of 0 - .3 mg/cm2. The critical limit of .1% was therefore not met. The analysis of the lead-included assemblers demonstrated measurements as low as 3.0 and as high as 5.0 mg/cm2.
Following four cross-contamination experiments with identical test boards, X-ray collected data from all areas of the assemblers showed that lead was neither transferred via redo reaction or ionic contamination. For the record, additional rinsing steps failed to alter the outcomes to any extent.
This test examined 500 lead-included assemblers that were cleaned using similar processes. Following the cleanings, lead-free test boards were cleaned using the exact same 'used cleaning agent at a wide array of temperatures. The lead content transfer, if any, was then analyzed and illustrated no significant increase in lead amounts in the lead-free assemblers.
The results demonstrate that a relatively small amount of lead is dissolved into a cleaning agent illustrating the ability to clean lead-free and lead-included agents using a single process without risk. It should be mentioned that the results seen only apply to individuals using similar cleaning agents to the ones used in testing. In contrast, it should be noted that cleaning agents with increased alkaline pH-values demonstrate a tendency to dissolve increased amounts of lead therefore increasing the risk of cross-contamination.
Results showed mixed cleaning process provide satisfactory results that meet current legislative requirements.
Test Provided by ZESTRON Europe, Ingolstadt, Germany
Click here for more news and industry related information resources.